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Guide to
| Surge Protection Devices
12
To gain maximum protection from the SPD, the connecting
conductors should be kept as short as possible. This is
to minimise any additive voltage drops on the connecting
cables.
The connecting conductors of the SPD shall have a cross
sectional area of not less than 4mm
2
copper and the total
connecting lead length (a+b) should preferably not exceed
0.5m but shall in no case exceed 1m.
Where Type 1 devices have been installed the cross section
area shall be not less than 16mm
2
copper. Manufacturer’s
instructions shall be followed.
Some devices have dual line & neutral terminals. This
connection method reduces any additional voltage drop in
the connecting cables thereby obtaining the best possible
U
p
to the installation. There are conditions to this connection
method however. With Hager devices it is suitable for
installations having a maximum demand up to 125A.
Connection
OCPD
SPD
a
b
Sensitive
Equipment
Main earthing terminal or
connecting conductor bar
OCPD = overcurrent protection device
SPD
= surge protection device